6Gb/s SATA 3.0 over eSATApd (12V/5V) cables

A number of years ago I came across an eSATA cable system known as eSATApd (5V/12V) DeLock was the first vendor I am aware of which sold these products. The key feature with this system is that it carries +12V with no mandated current limit. This makes it possible to power 3.5″ external hard disks from a PC without needing that pesky power brick.

Not DeLock or any other vendor produce enclosures that make use of this system, but that’s fine. They do sell the eSATApd connector and I’ve been modifying (in some cases, their own) enclosures for years to accept eSATApd power input.

DeLock 3.5" HDD enclosure modified with eSATApd connector to allow power-brick-less operation
DeLock 3.5″ HDD enclosure modified with eSATApd connector to allow power-brick-less operation

Recently I upped the ante by modifying a 2 bay RAID enclosure (using RAID 0) to accept eSATApd so I could power the entire enclosure from the PC. As you can typically get 12V/3A across these cables this should not have been a problem.

StarTech.com RAID enclosure modified with eSATApd connector, allowing use without the power brick
StarTech.com RAID enclosure modified with eSATApd connector, allowing use without the power brick

Except now I needed 6Gb/s SATA in order to get the benefits from the increased performance of the RAID 0 array. Suddenly, I’ve got a bit of a problem: These cables do not work at 6Gb/s.

This wasn’t entirely surprising to me. The specification for SATA is pretty clear about cables: The correct cable is a distinctive 100Ω impedance, flat twinaxial cable, whereas the DeLock/LINDY cable is a fairly thin and flexible round cable.

DSC_1241
An actual SATA cable showing the foam dielectric twinax data pairs

Another point that SATA-IO are clear about, is that there is no such thing as a 6Gb/s SATA cable. Cables that were properly designed for the original 1.5Gb/s interface should work just fine for 6Gb/s.

Notwithstanding this, I’m already suspicious about the construction of these cables. Let’s take a look at this one:

DSC_1247
First revision DeLock/LINDY eSATApd cable

As the DeLock cables I purchased are now pretty much useless to me, Let’s cut one open and see what’s in there:

DSC_1242
First revision DeLock/LINDY eSATApd cable

Well that clearly isn’t a very SATA looking cable. What appears to be in here is a couple of foil shielded PVC coated pairs of the same kind of construction that would be used in an HDMI cable.

Allow me to get out my Paint-fu to draw a little diagram of the two styles of cable:

 

That’s a pretty significant difference in design.

But despair not (?) DeLock seem now to be selling a newer version of this cable, which I’ve got a couple of. It’s a lot bulkier, with two fairly rigid cores bonded together. Perhaps this newer cable works at 6GB/s? Why else would they change the design. The old design, being thinner and several times more flexible, was a lot nicer to use.

Second revision DeLock eSATApd cable
Second revision DeLock eSATApd cable

Nope. This cable also doesn’t work at 6Gb/s. The system in most cases can’t detect the drive, and when it does detect it, file transfers frequently fail.

So now I’ve got another useless eSATA cable. Let’s cut this one open and see what’s going on:

DSC_1244
Second revision DeLock eSATApd cable

From what I can see, the core on the right is a “Powered USB” cable, this is typically used in conjunction with a specially designed connector for Retail/POS terminals which have a higher power requirement. This cable carries the +12V, +5V and USB 2.0, and is the correct type of cable for the USB half of this application.

The cable on the left is the one of interest as it carries the SATA signals. It appears to be of exactly the same construction as the previous edition of the cable – two foil shielded PVC coated pairs.

Whatever the reason these cables don’t work at 6Gb/s, they both have the same problem.

Success at last

DSC_1249

After hours of frustration – I found a very interesting looking cable on the U.S. Amazon site. Sold by “Micro SATA Cables“, it’s the first I’ve ever seen which uses proper SATA cable, bonded to a power cable. This is what I was looking for. Fortunately Amazon U.S. ships internationally, a week later I got a couple to try out.

Micro SATA Cabled eSATApd cable working at 6Gb/s
Micro SATA Cables eSATApd cable working at 6Gb/s

They work! Reliably sustaining the ~350MB/s my 2x6TB RAID 0 enclosure is capable of, and clearly surpassing the ~225MB/s limit of 3.0Gb/s SATA.

I don’t need to cut this cable open to know that it’s correctly designed. Aside from it actually working, the data wire is clearly labelled “Serial ATA”, and it also physically looks like SATA twinaxial cable.

Leave a Reply

Your email address will not be published. Required fields are marked *

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>